This is a U.S. national stage of application No. PCT/EP00/00571, filed on Jan. 26, 2000. Priority is claimed on that application and on the following application:
Country: Germany, Application No. 199 07 398.8, filed Feb. 20, 1999.
The invention pertains to an air intake system for an internal combustion engine, especially for a spark-ignition engine with direct injection, with a cylinder head delimiting at least one cylinder; with an intake manifold, which has at least one air passage per cylinder; and with at least one intake passage in the cylinder head per cylinder. An intake port of the passage leads into the associated cylinder. The intake manifold and the cylinder head are connected to each other by a cylinder head flange so that each air passage of the intake manifold is in fluid-conductive connection with its associated intake passage in the cylinder head. A flap valve which constricts the cross section of the air passage as desired is provided in the air passage of the intake manifold.
An intake passage system for an internal combustion engine with two intake passages per cylinder in one cylinder head is known from DE 3,836,550 C2. A flap valve, which completely closes one of the two intake passages as a function of the operating state of the internal combustible engine, is provided in an air intake manifold of the intake passage system. This system, however, suffers from the disadvantage that the wall separating the two passages must be designed to fit the flap valve with very close tolerances, and also the flap valve assembly must itself be fabricated with very close tolerances, so that one or the other of the two intake passages is sealed off completely. In addition, it is possible for one of the passages only to be opened or closed completely with this system. It is impossible to adjust the air flow in one passage. Furthermore, because of the manufacturing tolerances involved, the undesirable situation arises that only some of the flap valves, in the least favorable case only one valve, completely closes its intake passage, whereas the other valves leave a small gap. DE 3,522,991 A1 describes an internal combustion engine with an intake passage, where a swirl valve is provided in a rectangular section of the intake passage. Under certain operating conditions, an exception being operation at full load, this valve is opened in such a way that it produces a turbulent swirl flow into one of the cylinders of the engine. This design, however, is complicated, because each swirl valve must be controlled individually. In an alternative which is also mentioned, the air stream itself pushes the valve down to a greater or lesser degree. This suffers from the significant disadvantage, however, that, because the air stream must perform work, energy which would otherwise be available to the air stream itself is lost.
The present invention therefore has the task of making available an air intake system of the type described above which overcomes the disadvantages described above and which also makes it possible to shut off part of an intake passage, thus providing the opportunity to influence the movement of the charge into the combustion chamber of the internal combustion engine.
It is thus provided according to the invention that a partition wall is installed in the intake passage to divide the intake passage over a predetermined distance between the cylinder head flange and the intake port. Furthermore, the flap valve is designed in such a way and installed so as to project out over the cylinder head flange so that it strikes the partition wall when it is in the position where it constricts the cross section of the air passage.
This offers the advantage that, instead of the intake passage being completely closed off, the cross section of the air passage and that of the associated intake passage, under inclusion of the tumble plate, are merely constricted, so that, with a constant number of active intake passages, it becomes possible to influence the movement of the charge into the combustion chambers of the internal combustion engine in the desired manner.
All the flap valves can be actuated in common by providing a flap valve shaft in a wall of the intake manifold, to which shaft the flap valves of all the cylinders are connected, preferably by welding.
A fuel injection system which is simple and inexpensive with respect to both fabrication and assembly is obtained by providing a fuel injection device for each cylinder, by providing each of the fuel injection devices with a seat, which is designed to hold at least part of the fuel injection device, and by providing a fuel passage in the intake manifold, this fuel passage being connected to all the seats holding the fuel injection devices.
Because each flap valve is designed as a spring plate, these plates give way elastically after coming to rest against the partition wall until all of the flap valves have made contact with their associated partition walls. Thus, regardless of the angular tolerances present affecting the various flap valves of the cylinders, all of the flap valves will always seal off their section of the intake passage with the tightest possible seal.
Disturbances in the air flow in the air passage and in the intake passage caused by the flap valve are prevented by providing a recess in one of the walls of the air passage and/or in one of the walls of the intake passage. This recess is designed to accept at least part of the flap valve when the flap valve is in the position where it leaves the air passage and the intake passage completely open.
It is possible to obtain a good seal on one side of the partition wall despite a wide range of tolerances by bending the free end of the flap valve, i.e., the end which strikes the partition wall, by a predetermined angle.